Abstract
Hydrogen geo-storage is considered as an option for large scale hydrogen storage in a full-scale hydrogen economy. Among different types of subsurface formations, coal seams look to be one of the best suitable options as coal's micro/nano pore structure can adsorb a huge amount of gas (e.g. hydrogen) which can be withdrawn again once needed. However, literature lacks fundamental data regarding H
diffusion in coal.
In this study, we measured H
adsorption rate in an Australian anthracite coal sample at isothermal conditions for four different temperatures (20 °C, 30 °C, 45 °C and 60 °C), at equilibrium pressure ∼ 13 bar, and calculated H
diffusion coefficient ( [Formula: see text] ) at each temperature. CO
adsorption rates were measured for the same sample at similar temperatures and equilibrium pressure for comparison.
Results show that H
adsorption rate, and consequently [Formula: see text] , increases by temperature. [Formula: see text] values are one order of magnitude larger than the equivalent [Formula: see text] values for the whole studied temperature range 20-60 °C. [Formula: see text] / [Formula: see text] also shows an increasing trend versus temperature. CO
adsorption capacity at equilibrium pressure is about 5 times higher than that of H
in all studied temperatures. Both H
and CO
adsorption capacities, at equilibrium pressure, slightly decrease as temperature rises.